The helmets really are that big. There are quite a few left over from those days, and you can bet the designers had a close look at them. Logical, though. Chainmail coif, padding, and then the helmet. Just look at how big a motorcycle helmet is these days. And those don’t have spread wings or antlers…

On the detail: yes, they look kind of sparse, almost like some weird halfbreed between Airfix and tabletop minis. Also am never a fan of attached bases, which only strengthens the Airfix look.

I would like to buy sprues of just the heads. I’ve got some Black Templars that would look pretty swanky rocking some great-helms. (I know they’d be impractical in the 41st millenium, but at least it’s not bald and screaming)